Crazy-Paving Pattern Due to Herpetic Pneumonia in a Patient with Mycosis Fungoides: A Case Report.

Herpetic pneumonia in immune deficient patients could be fatal if not treated. Considering the low prevalence of this disease, computed tomography (CT) scan findings of this condition are not well elucidated. This report describes the CT scan findings of a patient with immune system deficiency due to mycosis fungoides, and pneumonia caused by herpes simplex virus 1 (HSV-1). Bilateral alveolar infiltration with crazy-paving pattern was observed on CT scan of the lungs. The scattered crazy-paving pattern noted in the CT scan of the lungs could be suggestive of herpetic pneumonia in immunocompromised patients presenting with lung infections.


INTRODUCTION
Respiratory infections are the most common invasive tissue infections in patients with immune deficiency (1).
Pneumonia caused by herpes simplex virus type 1 (HSV-1) is uncommon, but has been described as a fatal infection in immunocompromised individuals (1). Since the prevalence of this disease is quite low (except for patients with severe immunodeficiency), its radiographic findings have not been extensively described. However, early diagnosis is vital as the mortality rate associated with this disease, especially in untreated patients, is considerably high.
Mycosis fungoides (MF) is the most common type of non-Hodgkin's T-cell lymphoma which primarily affects the skin but eventually involves the lymph nodes and other organs (2) leading to humoral and cellular immune deficiency (3). Further, the risk of opportunistic infections, especially herpes, is significantly higher in these patients compared to healthy individuals (4). Pulmonary involvement is noted in 40 % to 60 % of cases of mycosis fungoides (5).
In immunocompromised patients presenting with symptoms of infectious diseases and pulmonary involvement, chest radiography is not sufficient and computed tomography (CT) scan should be suggested.
Although, some of the findings of CT scan are not specific, it helps to narrow down the differential diagnosis.
However, findings of CT scan in herpetic pneumonia are not widely reported.
In this case study, we report the CT scan findings of herpetic pneumonia in a patient with mycosis fungoides.

CASE SUMMARIES
The patient was a 60-year-old man, who was diagnosed with MF two years ago, and had been on retinoid compounds since one year. He had been experiencing weakness, lethargy, productive cough, dyspnea, chills, and Unfortunately, the patient passed away due to respiratory failure on the fifth day of the hospitalization, before antiviral therapy could be initiated. Lung biopsy did not reveal anything significant except for non-specific inflammation.  Herpes simplex virus, not only can cause pneumonia in babies but also in immunocompromised adults (1). In herpetic pneumonia, lung CT scan results are non-specific, and varied patterns such as diffuse ground glass opacity, diffuse nodules, and interlobular septal thickening, have been reported (6). In some of studies, ground glass opacity pattern has been reported as the main CT finding of herpetic pneumonia (6,7). In the study by Chong et al (6), the ground glass opacity was bilateral and diffuse or Ground glass opacity and crazy-paving patterns were the main patterns noted in CT scan in the current study.
Crazy-paving pattern refers to the combination of thickening of the interlobular septa and ground glass regions, which occurs due to alveolar involvement.
Although this finding was initially observed in patients with pulmonary alveolar proteinosis, it was later noted in many other diseases including infections, pulmonary edema, sarcoidosis, lipoid pneumonia, and diffuse pulmonary hemorrhage (8,9). In 50 % of patients with herpetic pneumonia, simultaneous presence of other pathogens can also be noted. Therefore, it appears that herpes simplex virus provides a suitable condition for other infections (14).
However, no other pathogen was identified in the current case.
In conclusion, crazy-paving pattern is one of the CT scan findings in herpetic pneumonia. As this pattern is non-specific in immunocompromised patients presenting with symptoms of infectious diseases, early collection of samples from the lung through invasive methods, is strongly recommended. This could help in initiating the anti-viral treatment early and can hence be life-saving.